OK, let's work through this together. We're starting with 654 and we're going to multiply it by 6, which means we add 654 to itself 6 times.
Step 1: 0 + 654 = 654
Step 2: 654 + 654 = 1308
Step 3: 1308 + 654 = 1962
Step 4: 1962 + 654 = 2616
Step 5: 2616 + 654 = 3270
Step 6: 3270 + 654 = 3924

So, 654*6 = 3924